Axial Flow Wind Wheel Blade Tip Section to Reduce Leakage Vortex Noise
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Solution Overview
Problem
Axial flow wind wheels in air conditioners generate significant noise due to leakage vortices at the blade tip, which increases with rotating speed, leading to increased noise levels.
Innovation Solution
The axial flow wind wheel design features blades with a top leaf margin that inclines from the pressure surface to the suction surface, with an inner edge that is concave and convex, creating a narrow section that reduces leakage vortex formation and noise by staggering airflow separations, thereby minimizing noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotating speed of the axial flow wind wheel is increased to improve air ventilation performance, then the air volume increases, but the noise generated by the axial flow wind wheel increases
Solution Approach 1:
The patent applies local quality by modifying only the blade tip region with a specific inclined section structure, while keeping the rest of the blade design conventional. This localized modification targets the specific area where leakage vortices form (at the blade tip) without changing the overall blade configuration, thereby reducing noise at the source while maintaining the blade's primary air-moving function.
Solution Approach 2:
The patent employs curvature by designing the blade tip with an inclined section that creates a smooth transitional surface rather than a sharp edge. The concave and convex inner edge configuration further refines this curvature to guide airflow smoothly, reducing turbulent eddies and vortex formation that cause noise during high-speed rotation.
2Productivity
If the blade tip rotational speed is maximized to improve air movement efficiency, then the air flow along the axial direction increases, but leakage vortex forms from the suction surface to the pressure surface resulting in large vortex noise
Solution Approach 1:
The inclined section with concave and convex inner edge creates a curved, streamlined blade tip geometry that guides airflow smoothly from the suction surface to the pressure surface. This curvature prevents the formation of sharp edges that would generate leakage vortices, thereby maintaining efficient air movement while reducing vortex-related noise.
Solution Approach 2:
The patent converts the potentially harmful leakage flow at the blade tip into a beneficial controlled flow pattern. By designing the inclined section, the natural pressure differential that causes leakage is harnessed to create a smooth flow transition rather than a violent vortex, turning a harmful effect into a beneficial airflow characteristic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively reduces noise levels by approximately 2 dB across various rotating speeds while maintaining air volume, with optimal noise reduction achieved when the tangential angle between the section and the pressure surface is between 10 and 20 degrees.
Implementation Method 1
the airflow passing through the tip position of the blade first flows to the section, and then flows along the inclining direction of the section. As the section is relatively narrow, the airflow hardly forms the leakage vortex on the section, that is, the airflow is gradually separated on the section
Implementation Method 2
Air around the axial flow wind wheel is driven by the axial flow wind wheel to rotate and form an airflow, to blow out along the axial direction of the axial flow wind wheel
Data Source
AI summary
The present disclosure provides an axial flow wind wheel and an air conditioner, the axial flow wind wheel includes a wheel hub and a plurality of blades, the blades are arranged on the wheel hub at intervals, the blade includes a front blade edge and a rear blade edge arranged from front to back, and a top blade edge connecting to outer ends of the front blade edge and the rear blade edge, the top blade edge defines a cut surface inclining from a pressure surface to a suction surface of the blade, and the cut surface extends from the front blade edge to the rear blade edge, the cut surface includes an outer cut edge defined at the top blade edge, and an inner cut edge defined at the pressure surface, and the inner cut edge is defined to concave inwards and protrude outwards, forming a concave-convex shape.